There is not easy way without editing an XLM file. If you decide to do this please make sure you have a backup of it.
You will need to go to C:\ProgramData\QlikTech\ManagementService\QVPR (default installation). There you will find the Category.xml and at the bottom is the Category names.
The line would look like this.
<Category Name="testing" ID="5ccdfd87-fbd2-4efe-8a2f-9905068cddea" ModifiedByUser="QV11\Administrator" ModifiedTime="2013-10-15T11:39:12.5462693-04:00" />
hi thank you for all who are in this discussion
but it is not working in my case i deleted the row from the category.xml yesterday and i checked on my QMC it did not get deleted in the category drop down list.
and today when i saw in the category.xml file i can see the deleted row.
do we need to do any other thing after deleted the below line from category.xml file.
i opened the category.xml file in notepad and deleted the row and saved it
<Category Name="Data" ID="a42c6f-f80-4fd-8a5-5b4de8" ModifiedByUser="*******" ModifiedTime="2013-12-20T19:03:13.068689-05:00" />